The present invention relates to methods of mounting electronic parts or components on a printed circuit board.
A conventional electronic part mounting system is shown in FIGS. 5 and 6. Electronic parts or components 1 each have a number of lead pins 1a each extending from a side first laterally and then downwardly for connection with a signal or power supply. These electronic parts 1 are mounted on a multilayer printed circuit board 2 which has a terminal 3 for connection with the outside.
As best shown in FIG. 6, each electronic part 1 is mounted on mounting lands 4 with solder 5 for connection with wiring patterns 6 which are formed on the surfaces or layers of the printed circuit board 2. A cylindrical conductou 7a is inserted in an aperture 7 which is formed through the respective layers of the board 2.
To mount electronic parts on a printed circuit board, first of all, creamy solder 5 is applied to the mounting lands 4 by the screen printing technique. Then, electronic parts 1 are attached to the soldered lands 4 with adhesive by an automatic mounting machine. The solder 5 is then melted to secure the lead pins 1a of the electronic part 1 to the mounting lands 4.
As the number of electronic parts 1 mounted on the surfaces of a printed circuit board 2 increases, the number of wiring patterns 6 increases, thus limiting the mounting space for the electronic parts. This problem is solved to a certain extent by increasing the number of layers of the printed circuit board 2. However, this technique increases the thickness of the board 2 and the unit manufacturing cost.